Solid-state imaging device, solid-state imaging device manufacturing method, electronic device, and lens array

ABSTRACT

A solid-state imaging device includes: multiple micro lenses, which are disposed in each of a first direction and a second direction orthogonal to the first direction, focus the incident light into the light-receiving surface; with the multiple micro lenses of which the planar shape is a shape including a portion divided by a side extending in the first direction and a side extending in the second direction being disposed arrayed mutually adjacent to each of the first direction and the second direction; and with the multiple micro lenses being formed so that the depth of a groove between micro lenses arrayed in a third direction is deeper than the depth of a groove between micro lenses arrayed in the first direction, and also the curvature of the lens surface in the third direction is higher than the curvature of the lens surface in the first direction.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/926,923, filed Oct. 29, 2015, which is acontinuation application of U.S. patent application Ser. No. 14/166,310,filed Jan. 28, 2014, now U.S. Pat. No. 9,202,836, which is a divisionalapplication of U.S. patent application Ser. No. 12/886,952, filed Sep.21, 2010, now U.S. Pat. No. 8,686,337, which claims the priority fromprior Japanese Priority Patent Application JP 2009-225159 filed Sep. 29,2009, the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid-state imaging device, asolid-state imaging device manufacturing method, an electronic device,and a lens array.

2. Description of the Related Art

Cameras such as digital video cameras and digital still cameras includesolid-state imaging devices, e.g., include CMOS (Complementary MetalOxide Semiconductor) image sensors or CCD (Charge Coupled Device) imagesensors as a solid-state imaging device.

With solid-state imaging devices, an imaging region where multiplepixels are formed is provided to the surface of the semiconductorsubstrate. With this imaging region, multiple photoelectric conversionunits which receive light according to a subject image, and generatesignal charge by subjecting the received light thereof to photoelectricconversion, are formed so as to correspond to the multiple pixelsthereof. For example, photodiodes are formed as the photoelectricconversion units.

Of solid-state imaging devices, with CCD-type image sensors, a verticaltransfer register unit is provided between multiple pixel columnsarrayed in the vertical direction. With vertical transfer registerunits, multiple transfer electrodes are provided so as to face avertical transfer channel region via a gate insulating film, whichtransfer signal charge read out from a photoelectric conversion unit bya charge readout unit in the vertical direction. Subsequently, thesignal charge transferred for each one horizontal line (pixels in onerow) by the vertical transfer register unit thereof is transferred inthe horizontal direction by a horizontal transfer register unit, and isoutput by an output unit.

Also, of solid-state imaging devices, with CMOS-type image sensors,pixels are configured so as to include multiple transistors in additionto photoelectric conversion units. The multiple transistors areconfigured as a pixel transistor which reads out the signal chargegenerated by a photoelectric conversion unit to output this to a signalline as an electric signal. Also, with CMOS-type image sensors, in orderto reduce the pixel size, it has been proposed that the pixels beconfigured so that the multiple photoelectric conversion units share theabove pixel transistor. For example, a technique has been proposedwherein two or four photoelectric conversion units share a single pixeltransistor group (e.g., see Japanese Unexamined Patent ApplicationPublication No. 2004-172950).

With solid-state imaging devices, in general, a “front illumination”type has been familiar wherein photoelectric conversion units receivelight to be input from the surface side where circuit elements andwirings and so forth are provided on the semiconductor substrate. In thecase of the front illumination type, there is a case where it isdifficult to improve sensitivity since a circuit element or wiring orthe like shield or reflect light to be input thereto. Therefore, a“backside illumination” type has been proposed wherein photoelectricconversion units receive light to be input from the rear surface sidethat is the opposite side of the surface where circuit elements,wirings, and so forth are provided on the semiconductor substrate (e.g.,see Japanese Unexamined Patent Application Publication No. 2003-31785).

With a solid-state imaging device such as described above, as the numberof pixels increases, the cell size of each pixel becomes small. As aresult thereof, light receiving amount per one pixel may decrease.

Therefore, in order to enhance the light collection efficiency andincrease the amount of light received, an on-chip lens is provided.Specifically, a micro lens for focusing light onto the light-receivingsurface of a photoelectric conversion unit is provides so as tocorrespond to each pixel (e.g., see Japanese Unexamined PatentApplication Publication Nos. 2000-039503 and 2000-206310).

With micro lens forming process, for example, a micro lens materialconfigured of a photosensitive resin is subjected to pattern processingon a flattened film (or undercoating of a micro lens) disposed on acolor filter by photolithography technology. Subsequently, the processedmicro lens material is subjected to bleaching exposure, and issubsequently subjected to a reflow process, and accordingly a micro lensis formed (e.g., see Japanese Unexamined Patent Application PublicationNos. 2003-222705, 2007-294779, and 2007-025383).

In addition, after a mask layer is formed on a lens material layer, amicro lens is formed by subjecting the lens material layer to etchingprocessing using the mask layer thereof. Specifically, first, after aphotosensitive resin film is formed on the lens material layer, thephotosensitive resin is subjected to pattern processing byphotolithography to form a resist pattern so as to correspond to aregion where a micro lens is formed. Subsequently, a reflow process forheating and melting the resist pattern is carried out to transform theresist pattern thereof into the shape of the lens, thereby forming amask layer. Subsequently, both of the resist pattern transformed intothe mask layer thereof, and the lens material layer are subjected toetchback, and accordingly, the lens material layer located under themask layer is processed into a macro lens (e.g., see Japanese Patent No.4186238, and Japanese Unexamined Patent Application Publication No.2007-53318).

SUMMARY OF THE INVENTION

However, in the event that a micro lens is formed by subjecting thepattern-processed lens material layer to a reflow process (in the caseof the former manufacturing method), an inconvenience may be caused,such as increase in cost, difficulty in manufacturing in a stablemanner, or the like. In particular, in order to prevent adjacent microlenses from being fused and the shapes thereof from collapsing by thereflow process, when taking various types of measures, occurrence ofthis inconvenience becomes prominent. For example, increase in cost maybe caused due to having to use an expensive photo mask (JapaneseUnexamined Patent Application Publication No. 2007-316153), increase inthe number of processes, having to invest in facilities, or the like.Also, a product may not readily be manufactured in a stable manner dueto unevenness between material lots of new materials, or unevennessbetween process conditions (e.g., see Japanese Unexamined PatentApplication Publication Nos. 2000-206310, 2003-222705, 2007-316153, and2007-294779).

Also, even when forming a micro lens by subjecting the lens materiallayer to etchback using a mask layer processed into a lens shape (in thecase of the latter manufacturing method), the same inconvenience as theabove may be caused. With this manufacturing method, the effective areasof micro lenses can readily be enlarged, but distance between the microlenses is longer in the diagonal directions of the lenses compared tothe side directions, and accordingly, etchback has to be performed for along time, which incurs deterioration in dark current or the like, andthe image quality of an imaged image may deteriorate (e.g., see JapaneseUnexamined Patent Application Publication No. 2007-025383 and JapanesePatent No. 4186238).

Thus, with micro lens manufacturing, it may be difficult to form microlens with high precision, and focusing efficiency may not readily beimproved. Further, inconvenience may be caused such as increase in cost,deterioration in manufacturing efficiency, or the like.

The image quality of an imaged image may deteriorate due to the abovecauses. Specifically, in the case of a CCD type, inconvenience mayoccur, such as deterioration in sensitivity, occurrence of smear,shading, or color mixture, or the like.

FIG. 25 is a diagram illustrating the results of optical simulation byFTDT (Finite Difference Time Domain). Here, with a CCD solid-stateimaging device, the results of sensitivity and smear property in theevent that of changing the film thickness of a micro lens with the pixelsize being a tetragonal lattice of 1.55 μm.

As illustrated in FIG. 25, when increasing the film thickness of a microlens, the sensitivity increases, but the smear property deteriorates.Therefore, both of the properties are not readily improved, and imagequality is not readily improved.

Also, in the case of a CMOS type, inconvenience may be caused, such asdeterioration in sensitivity, occurrence of color mixture, or the like.In particular, in the case of the above “backside illumination” type,occurrence of inconvenience due to color mixture between adjacent pixelsmay become prominent. Thus, it may be difficult to improve the imagequality of an imaged image.

It has been found to be desirable to provide a solid-state imagingdevice, a solid-state imaging device manufacturing method, an electronicdevice, and a lens array, whereby focusing efficiency can be improved byforming a micro lens with high precision, and the image quality of animaged image can readily be improved.

An embodiment of the present invention is a solid-state imaging deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a plurality of micro lenses, whichare disposed in each of the first direction and the second directionabove each light-receiving surface of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a transfer unit, which is provided for eachcolumn of the plurality of photoelectric conversion units arrayed in thesecond direction of the plurality of photoelectric conversion units,where a transfer channel region configured to transfer signal chargegenerated at this photoelectric conversion unit in the second directionis formed on the imaging face; with the plurality of micro lenses ofwhich the planar shape of the imaging face is a shape including aportion divided by a side extending in the first direction and a sideextending in the second direction being disposed so as to be arrayedmutually adjacent to each of the first direction and the seconddirection; and with the plurality of micro lenses being formed so thatthe depth of a groove between micro lenses arrayed in a third directioninclined in the first direction and the second direction of the imagingface is deeper than the depth of a groove between micro lenses arrayedin the first direction, and also the curvature of the lens surface inthe third direction is higher than the curvature of the lens surface inthe first direction.

The plurality of micro lenses may be formed so that the depth of agroove between micro lenses arrayed in the second direction is deeperthan the depth of a groove between micro lenses arrayed in the firstdirection, and also the curvature of the lens surface in the seconddirection is formed so as to be higher than the curvature of the lenssurface in the first direction.

With the plurality of micro lenses, depth D1 of a groove between microlenses arrayed in the first direction, and depth D3 of a groove betweenmicro lenses arrayed adjacent to the third direction may have a relationof D1:D3=1:3 to 5.

With the plurality of micro lenses, depth D1 of a groove between microlenses arrayed in the first direction may have a relation of D1≤150 nm.

An embodiment of the present invention is a solid-state imaging deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a micro lens, which is disposed aboveeach light-receiving surface of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a transfer unit, which is provided for eachcolumn of the plurality of photoelectric conversion units arrayed in thesecond direction of the plurality of photoelectric conversion units,where a transfer channel region configured to transfer signal chargegenerated at this photoelectric conversion unit in the second directionis formed on the imaging face; with the micro lens being formed so thatthe lens surface to which the incident light is input becomes a curvedsurface in the second direction, and becomes a planar surface in thefirst direction.

An embodiment of the present invention is a solid-state imaging deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a plurality of micro lenses, whichare disposed in each of the first direction and the second directionabove each light-receiving surface of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a pixel transistor, which is providedbetween the plurality of photoelectric conversion units of the imagingface, configured to read out and output signal charge generated at theplurality of photoelectric conversion units; with the plurality of microlenses of which the planar shape of the imaging face is a shapeincluding a portion divided by a side extending in the first directionand a side extending in the second direction being disposed so as to bearrayed mutually adjacent to each of the first direction and the seconddirection; and with the plurality of micro lenses being formed so thatthe depth of a groove between micro lenses corresponding to a portionwhere the plurality of photoelectric conversion units are arrayedwithout the pixel transistor introduced therebetween at the imaging faceis deeper than the depth of a groove between micro lenses of otherportions, and also the curvature of the lens surface on the side of aportion where the plurality of photoelectric conversion units arearrayed without the plurality of pixel transistors introducedtherebetween is higher than the curvature of the lens surface of otherportions.

An embodiment of the present invention is a solid-state imaging devicemanufacturing method including: first forming, of a plurality ofphotoelectric conversion units which receive incident light at areceiving surface to generate signal charge so as to be arrayed in eachof a first direction and a second direction orthogonal to the firstdirection of an imaging face of a substrate; second forming, of atransfer unit where a transfer channel region transfers signal charge tobe generated at the plurality of photoelectric conversion units in thesecond direction, for each column of the plurality of photoelectricconversion units arrayed in the second direction of the plurality ofphotoelectric conversion units; and third forming, of a plurality ofmicro lenses which focus the incident light onto the light-receivingsurface so that the plurality of micro lenses are arrayed in each of thefirst direction and the second direction above each light-receivingsurface of the plurality of photoelectric conversion units; with theplurality of micro lenses being formed in the third forming so that theplanar shape of the imaging face is a shape including a portion dividedby a side extending in the first direction and a side extending in thesecond direction are disposed so as to be arrayed mutually adjacent toeach of the first direction and the second direction; and with theplurality of micro lenses being formed so that the depth of a groovebetween micro lenses arrayed in a third direction inclined in the firstdirection and the second direction of the imaging face is deeper thanthe depth of a groove between micro lenses arrayed in the firstdirection, and also the curvature of the lens surface in the thirddirection is higher than the curvature of the lens surface in the firstdirection.

The third forming may include: fourth forming, of a lens material layeron the substrate; fifth forming, of a resist pattern on the lensmaterial layer; a heating reflow process, of the resist pattern; andlens material layer processing, of the resist pattern subjected to theheating reflow process and the lens material layer, by performing anetchback process, so as to pattern-process the lens material layer intothe micro lens.

The heating reflow process may be carried out regarding the resistpattern so that resist patterns arrayed adjacent to the third directionof the imaging face maintain a separated state, and also resist patternsarrayed in the first direction are mutually fused.

In the heating reflow process, a post bake process may be carried out aplurality of number of times as the heating reflow process so that ofthe post bake processes of the plurality of number of times, a post bakeprocess carried out later is higher in heat processing temperature thana post bake process carried out earlier.

In the third forming, the plurality of micro lenses may be formed sothat the depth of a groove between micro lenses arrayed in the seconddirection is deeper than the depth of a groove between micro lensesarrayed in the first direction, and also the curvature of the lenssurface in the second direction is higher than the curvature of the lenssurface in the first direction.

An embodiment of the present invention is a solid-state imaging devicemanufacturing method including: first forming, of a plurality ofphotoelectric conversion units which receive incident light at areceiving surface to generate signal charge so as to be arrayed in eachof a first direction and a second direction orthogonal to the firstdirection of an imaging face of a substrate; second forming, of atransfer unit where a transfer channel region transfers signal charge tobe generated at the plurality of photoelectric conversion units in thesecond direction, for each column of the plurality of photoelectricconversion units arrayed in the second direction of the plurality ofphotoelectric conversion units; and third forming, of a plurality ofmicro lenses which focus the incident light onto the light-receivingsurface above each light-receiving surface of the plurality ofphotoelectric conversion units; with the plurality of micro lenses beingformed in the micro lens forming step, so that the lens surface to whichthe incident light is input becomes a curved surface in the seconddirection, and becomes a planar surface in the first direction.

An embodiment of the present invention is a solid-state imaging devicemanufacturing method including: first forming, of a plurality ofphotoelectric conversion units which receive incident light at areceiving surface to generate signal charge so as to be arrayed in eachof a first direction and a second direction orthogonal to the firstdirection of an imaging face of a substrate; second forming, of a pixeltransistor which reads out and outputs signal charge generated at theplurality of photoelectric conversion units, between the plurality ofphotoelectric conversion units of the imaging face; and third forming,of a plurality of micro lenses which focus the incident light onto thelight-receiving surface so that the plurality of micro lenses arearrayed in each of the first direction and the second direction aboveeach light-receiving surface of the plurality of photoelectricconversion units; with the plurality of micro lenses being formed in themicro lens forming step, so that the planar shape of the imaging face isa shape including a portion divided by a side extending in the firstdirection and a side extending in the second direction are disposed soas to be arrayed mutually adjacent to each of the first direction andthe second direction; and with the plurality of micro lenses beingformed so that the depth of a groove between micro lenses correspondingto a portion where the plurality of photoelectric conversion units arearrayed without the plurality of pixel transistors introducedtherebetween at the imaging face is deeper than the depth of a groovebetween micro lenses of other portions, and also the curvature of thelens surface in a portion where the plurality of photoelectricconversion units are arrayed without the plurality of pixel transistorsintroduced therebetween is higher than the curvature of the lens surfaceof other portions.

An embodiment of the present invention is an electronic deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a plurality of micro lenses, whichare disposed in each of the first direction and the second directionabove each light-receiving surface of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a transfer unit, which is provided for eachcolumn of the plurality of photoelectric conversion units arrayed in thesecond direction of the plurality of photoelectric conversion units,where a transfer channel region configured to transfer signal chargegenerated at this photoelectric conversion unit in the second directionis formed on the imaging face; with the plurality of micro lenses ofwhich the planar shape of the imaging face is a shape including aportion divided by a side extending in the first direction and a sideextending in the second direction being disposed so as to be arrayedmutually adjacent to each of the first direction and the seconddirection; and with the plurality of micro lenses being formed so thatthe depth of a groove between micro lenses arrayed in a third directioninclined in the first direction and the second direction of the imagingface is deeper than the depth of a groove between micro lenses arrayedin the first direction, and also the curvature of the lens surface inthe third direction is higher than the curvature of the lens surface inthe first direction.

An embodiment of the present invention is an electronic deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a micro lens, which is disposed abovethe light-receiving surfaces of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a transfer unit, which is provided for eachcolumn of the plurality of photoelectric conversion units arrayed in thesecond direction of the plurality of photoelectric conversion units,where a transfer channel region configured to transfer signal chargegenerated at this photoelectric conversion unit in the second directionis formed on the imaging face; with the micro lens being formed so thatthe lens surface to which the incident light is input becomes a curvedsurface in the second direction, and becomes a planar surface in thefirst direction.

An embodiment of the present invention is an electronic deviceincluding: a plurality of photoelectric conversion units, which aredisposed so as to be arrayed in each of a first direction and a seconddirection orthogonal to the first direction of an imaging face of asubstrate, configured to receive incident light at a light-receivingsurface to generate signal charge; a plurality of micro lenses, whichare disposed in each of the first direction and the second directionabove each light-receiving surface of the plurality of photoelectricconversion units, configured to focus the incident light onto thelight-receiving surface; and a pixel transistor, which is providedbetween the plurality of photoelectric conversion units of the imagingface, configured to read out and output signal charge generated at theplurality of photoelectric conversion units; with the plurality of microlenses of which the planar shape at the imaging face is a shapeincluding a portion divided by a side extending in the first directionand a side extending in the second direction being disposed so as to bearrayed mutually adjacent to each of the first direction and the seconddirection; and with the plurality of micro lenses being formed so thatthe depth of a groove between micro lenses corresponding to a portionwhere the plurality of photoelectric conversion units are arrayedwithout the pixel transistor introduced therebetween at the imaging faceis deeper than the depth of a groove between micro lenses of otherportions, and also the curvature of the lens surface in a portion wherethe plurality of photoelectric conversion units are arrayed without thepixel transistor introduced therebetween is higher than the curvature ofthe lens surface of other portions.

An embodiment of the present invention is a lens array including: aplurality of micro lenses, which are disposed so as to be arrayed ineach of a first direction and a second direction orthogonal to the firstdirection, configured to focus incident light; with the plurality ofmicro lenses of which the planar shape is a shape including a portiondivided by a side extending in the first direction and a side extendingin the second direction being disposed so as to be arrayed mutuallyadjacent to each of the first direction and the second direction; andwith the plurality of micro lenses being formed so that the depth of agroove between micro lenses arrayed in a third direction inclined in thefirst direction and the second direction is deeper than the depth of agroove between micro lenses arrayed in the first direction, and also thecurvature of the lens surface in the third direction is higher than thecurvature of the lens surface in the first direction.

The plurality of micro lenses may be formed so that the depth of agroove between micro lenses arrayed in the second direction is deeperthan the depth of a groove between micro lenses arrayed in the firstdirection, and also the curvature of the lens surface in the seconddirection is higher than the curvature of the lens surface in the firstdirection.

With the above configurations, the micro lenses are high in thecurvature of the micro lenses in the diagonal direction (the lensthickness is thick), and accordingly, for example, can effectively focusincident light onto the light-receiving surface from the diagonaldirection where smear is prevented from occurring with a CCD type.Subsequently, sensitivity can be improved along with this.

According to the above configurations, a solid-state imaging device, asolid-state imaging device manufacturing method, an electronic device,and a lens array can be provided, wherein focusing efficiency can beimproved by forming micro lenses with high precision, and the imagequality of an imaged image can readily be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram illustrating the configuration of acamera according to a first embodiment according of the presentinvention;

FIG. 2 is a plan view schematically illustrating the overallconfiguration of a solid-state imaging device according to the firstembodiment of the present invention;

FIG. 3 is a diagram illustrating the principal portions of thesolid-state imaging device according to the first embodiment of thepresent invention;

FIG. 4 is a diagram illustrating a color filter according to the firstembodiment of the present invention;

FIGS. 5A and 5B are diagrams illustrating a micro lens according to thefirst embodiment of the present invention;

FIG. 6 is a diagram illustrating the micro lens according to the firstembodiment of the present invention;

FIG. 7 is a diagram illustrating the principal portions provided at eachprocess of the manufacturing method of the solid-state imaging deviceaccording to the first embodiment of the present invention;

FIG. 8 is a diagram illustrating the principal portions provided at eachprocess of the manufacturing method of the solid-state imaging deviceaccording to the first embodiment of the present invention;

FIG. 9 is a diagram illustrating a photo mask to be used at a resistpattern forming process according to the first embodiment of the presentinvention;

FIG. 10 is a diagram illustrating the principal portions of asolid-state imaging device according to a second embodiment of thepresent invention;

FIG. 11 is a diagram illustrating the principal portions provided ateach process of the manufacturing method of the solid-state imagingdevice according to the second embodiment of the present invention;

FIG. 12 is a diagram illustrating a photo mask to be used at a resistpattern forming process according to the second embodiment of thepresent invention;

FIGS. 13A and 13B are diagrams illustrating the principal portions of asolid-state imaging device according to a third embodiment of thepresent invention;

FIG. 14 is a diagram illustrating the principal portions provided ateach process of the manufacturing method of the solid-state imagingdevice according to the third embodiment of the present invention;

FIG. 15 is a diagram illustrating the principal portions of asolid-state imaging device according to a fourth embodiment of thepresent invention;

FIG. 16 is a diagram illustrating the principal portions of thesolid-state imaging device according to the forth embodiment of thepresent invention;

FIG. 17 is a diagram illustrating the principal portions of thesolid-state imaging device according to the forth embodiment of thepresent invention;

FIG. 18 is a diagram illustrating a micro lens according to the fourthembodiment of the present invention;

FIG. 19 is a diagram illustrating the micro lens according to the fourthembodiment of the present invention;

FIG. 20 is a diagram illustrating the principal portions of a solidstate imaging device according to an embodiment of the presentinvention;

FIG. 21 is a diagram illustrating the principal portions of a solidstate imaging device according to an embodiment of the presentinvention;

FIG. 22 is a diagram illustrating the principal portions of a solidstate imaging device according to an embodiment of the presentinvention;

FIG. 23 is a diagram illustrating the principal portions of a solidstate imaging device according to an embodiment of the presentinvention;

FIG. 24 is a diagram illustrating the principal portions of a solidstate imaging device according to an embodiment of the presentinvention; and

FIG. 25 is a diagram illustrating the results of an optical simulationby FTDT.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, embodiments of the present invention will be described withreference to the drawings. Note that description will be made inaccordance with the following sequence.

1. First Embodiment (Case where the curvature in the diagonal directionof OCL is higher than that in the horizontal direction at a CCD type)

2. Second Embodiment (Case where the curvature in the diagonal andvertical directions of OCL is higher than that in the horizontaldirection at the CCD type)

3. Third Embodiment (Case where the shape of OCL is a dome-like shape atthe CCD type)

4. Fourth Embodiment (Case of a CMOS type)

5. Others

1. First Embodiment A. Device Configuration, Etc.

A-1. Principal Portion Configuration of a Camera

FIG. 1 is a configuration diagram illustrating the configuration of acamera 200 according to a first embodiment of the present invention. Asillustrated in FIG. 1, the camera 200 includes a solid-state imagingdevice 1, an optical system 202, a driving circuit 203, and a signalprocessing circuit 204.

The solid-state imaging device 1 is configured so as to output signalcharge generated by imaging light (subject image) H to be input via theoptical system 202 at an imaging face PS, as raw data. The detailedconfiguration of the solid-state imaging device 1 will be describedlater.

The optical system 202 includes, for example, an optical lens anddiaphragm, and carries out image formation of the input light H on theimaging face PS of the solid-state imaging device 1.

The driving circuit 203 outputs various types of driving signals to thesolid-state imaging device 1 and the signal processing circuit 204 todrive the solid-state imaging device 1 and the signal processing circuit204, respectively.

The signal processing circuit 204 generates a digital image regarding asubject image by subjecting the raw data output from the solid-stateimaging device 1 to signal processing.

A-2. Overall Configuration of the Solid State Imaging Device

FIG. 2 is a plan view schematically illustrating the overallconfiguration of the solid-state imaging device 1 according to the firstembodiment of the present invention. As illustrated in FIG. 2, thesolid-state imaging device 1 is, for example, a CCD-type image sensoraccording to the interline method, and a subject image is imaged in animaging region PA.

With the imaging region PA, such as illustrated in FIG. 2, a pixel P, acharge readout unit RO, and a vertical transfer register unit VT areformed.

As illustrated in FIG. 2, multiple pixels P are provided to the imagingregion PA, and each of the pixels P is disposed so as to be arrayed in amatrix manner in a horizontal direction x and in a vertical direction y.Each of the pixels P includes a photoelectric conversion element, wherelight is received at a light-receiving surface JS to generate signalcharge. Subsequently, with the circumference of the multiple pixels P,an element separating unit SS is provided so as to separate the pixelsP. Subsequently, each of the pixels P is configured to generate signalcharge by receiving light serving as a subject image at thelight-receiving surface JS to perform photoelectric conversion.

Multiple charge readout units RO are provided so as to correspond to themultiple pixels P on the imaging region PA such as illustrated in FIG.2, and are configured to read out the signal charge generated at thepixel P thereof to the vertical transfer register unit VT thereof.

The vertical transfer register unit VT extends in a vertical direction yso as to correspond to the multiple pixels P arrayed in the verticaldirection y on the imaging region PA, such as illustrated in FIG. 2.Also, the vertical transfer register unit VT is disposed between thecolumns of the pixels P arrayed in the vertical direction y. Two or morevertical transfer register units VT are provided to the imaging regionPA, and are arrayed in a horizontal direction x so as to correspond tothe multiple pixels P arrayed in the horizontal direction xrespectively. Each of the vertical transfer register units VT is avertical transfer CCD, wherein signal charge is read out from the pixelP thereof via the charge readout unit RO thereof, and is transferred inthe vertical direction y. With each of the vertical transfer registerunits VT, multiple transfer electrodes (not illustrated) are disposed soas to be arrayed in the vertical direction y, and for example, a 4-phasedriving pulse signal is sequentially supplied to the transfer electrodesarrayed in the vertical direction, thereby transferring the signalcharge. That is to say, each of the vertical transfer register units VTis provided for each column of the multiple pixels P arrayed in thevertical direction y of the multiple pixels P, and a transfer channelregion is formed on the imaging face wherein the signal charge generatedat each of the pixels P is transferred in the vertical direction y.

With the lower edge portion of the imaging region PA, such asillustrated in FIG. 2, a horizontal transfer register unit HT isdisposed. This horizontal transfer register unit HT extends in thehorizontal direction x, and sequentially transfers the signal chargetransferred in the vertical direction y from each of the multiplevertical transfer register units VT. That is to say, the horizontaltransfer register unit HT is a horizontal transfer CCD, and is driven bya two-phase driving pulse signal to transfer the signal chargetransferred for each horizontal line (pixels in one row).

With the left edge portion of the horizontal transfer register unit HT,such as illustrated in FIG. 2, an output unit OUT is formed, and thisoutput unit OUT converts the signal charge horizontally transferred bythe horizontal transfer register unit HT into voltage, and outputs thisas an analog image signal. Note that the above imaging region PA isequivalent to the imaging face PS illustrated in FIG. 1.

A-3. Detailed Configuration of the Solid-State Imaging Device

The detailed configuration of the above solid-state imaging device 1will be described. FIG. 3 is a diagram illustrating the principalportions of the solid-state imaging device 1 according to the firstembodiment of the present invention. Here, FIG. 3 illustrates thecross-section of the principal portions.

The solid-state imaging device 1 includes, such as illustrated in FIG.3, a substrate 101. The substrate 101 is, for example, an n-type siliconsemiconductor substrate, and a photodiode 21, a charge readout channelregion 22R, a charge transfer channel region 23T, and a channel stopperregion 24C are provided within this substrate 101.

As illustrated in FIG. 3, a transfer electrode 31, a metallight-shielding film 41, an intra-layer lens 45, a color filter 51, anda micro lens 61 are provided to the surface of the substrate 101. Eachunit making up the solid-state imaging device 1 will be described inorder.

(1) About the Photodiode 21

Photodiodes 21 are, such as illustrated in FIG. 3, provided to thesubstrate 101 so as to correspond to the pixels P. That is to say, themultiple photodiodes 21 are disposed so as to be arrayed in each of thehorizontal direction x and the vertical direction y orthogonal to thehorizontal direction x on the imaging face of the substrate 101. Thisphotodiode 21 is configured to receive light at the light-receivingsurface JS, and subject the light to photoelectric conversion, therebygenerating signal charge.

Specifically, the photodiode 21 is provided to a portion located on thesurface side within the substrate 101. Though drawing thereof isomitted, the photodiode 21 is configured by an n-type semiconductorregion (n) (not illustrated) and a p-type semiconductor region (p+) (notillustrated) being sequentially formed on the p-type semiconductor wellregion (p) (not illustrated) formed within the substrate 101, forexample.

Here, the n-type semiconductor region (n) serves as a signal chargeaccumulation region. The p-type semiconductor region (p+) serves as apositive hole accumulation region, and is configured so as to preventdark current from occurring on the n-type semiconductor region (n) thatis a signal charge accumulation region.

With the photodiode 21, an intra-layer lens 45, a color filter 51, amicro lens 61, and so forth are provided above the light-receivingsurface JS using a material for transmitting light. Therefore, thephotodiode 21 sequentially receives light H to be input via each ofthese at the light-receiving surface JS to generate signal charge.

(2) About the Charge Readout Channel Region 22R

The charge readout channel region 22R is, such as illustrated in FIG. 3,provided so as to correspond to the charge readout unit RO, and isconfigured to read out the signal charge generated at the photodiode 21.

Specifically, the charge readout channel region 22R is, such asillustrated in FIG. 3, provided so as to be adjacent to the photodiode21 at a portion located on the surface side within the substrate 101.

Here, the charge readout channel region 22R is disposed on the left sideof the photodiode 21 in the horizontal direction x. For example, thecharge readout channel region 22R is configured as a p-typesemiconductor region.

(3) About the Charge Transfer Channel Region 23T

The charge transfer channel region 23T is, such as illustrated in FIG.3, provided so as to correspond to the vertical transfer register unitVT, and is configured to transfer the signal charge read out from thephotodiode 21 by the charge readout unit RO using the charge transferchannel region 23T.

Specifically, the charge transfer channel region 23T is, such asillustrated in FIG. 3, provided adjacent to the charge readout channelregion 22R on a portion located on the surface side within the substrate101.

Here, the charge transfer channel region 23T is disposed on the leftside of the charge readout channel region 22R in the horizontaldirection x. For example, the charge transfer channel region 23T isconfigured by providing the n-type semiconductor region (n) (notillustrated) above the p-type semiconductor region (p) (not illustrated)within the substrate 101.

(4) About the Channel Stopper Region 24C

The channel stopper region 24C is, such as illustrated in FIG. 3,provided so as to correspond to the element separating unit SS.Specifically, the channel stopper region 24C is, such as illustrated inFIG. 3, provided to a portion located on the surface side within thesubstrate 101.

Here, the channel stopper region 24C is provided on the left side of thecharge readout channel region 22R in the horizontal direction x such asillustrated in FIG. 2 so as to be introduced between the charge readoutchannel region 22R and the photodiode 21 disposed in an adjacent column.In addition, the channel stopper region 24C is provided so as tocorrespond to the element separating unit SS of two photodiodes 21arrayed in the vertical direction y (see FIG. 2).

This channel stopper region 24C is configured, for example, by providingthe p-type semiconductor region (p+) (not illustrated) above the p-typesemiconductor well region (p) (not illustrated) within the substrate101, and preventing signal charge from inflow/outflow by forming apotential barrier.

(5) About the Transfer Electrode 31

The transfer electrode 31 is, such as illustrated in FIG. 3, provided soas to face the surface of the substrate 101 via a gate insulating filmGx. The transfer electrode 31 is formed of an electroconductivematerial. For example, the transfer electrode 31 is formed using anelectrical conducting material such as polysilicon, and is provided onthe gate insulating film Gx formed of a silicon dioxide film, forexample.

(6) About the Metal Light-Shielding Film 41

The metal light-shielding film 41 is, such as illustrated in FIG. 3,formed above the charge readout channel region 22R and the chargetransfer channel region 23T on the surface of the substrate 101, andshields light input to the charge readout channel region 22R and thecharge transfer channel region 23T. Also, the metal light-shielding film41 is, such as illustrated in FIG. 3, provided so as to cover thetransfer electrode 31 via an insulating film Sz.

Here, metal light-shielding films 41 are formed in a region other than aregion corresponding to the light-receiving surface JS, above thesubstrate 101. Each of the metal light-shielding films 41 is formed of alight-shielding material for shielding light. For example, the metallight-shielding film 41 is formed using a metal material such astungsten, aluminum, or the like.

(7) About the Intra-Layer Lens 45

The intra-layer 45 is, such as illustrated in FIG. 3, provided so as tocorrespond to the light-receiving surface JS above the surface of thesubstrate 101. Two or more intra-layer lenses 45 are arrayed with thesame shape so as to correspond to the multiple pixels P arrayed in theimaging region PA.

Here, the intra-layer lens 45 is a convex lens formed with the centerbeing thicker than the edge in a direction from the light-receivingsurface JS to the color filter 51 side, and is configured to focus theincident light H onto the center of the light-receiving surface JS.

(8) About the Color Filter 51

The color filter 51 is, such as illustrated in FIG. 3, provided so as toface the light-receiving surface JS via the intra-layer lens 45 abovethe surface of the substrate 101. The color filter 51 is provided on theupper surface of flattening film HT1 for flattening the surface of theintra-layer lens 45. Here, the color filter 51 is configured to colorthe incident light H to transmit this to the light-receiving surface JS.

FIG. 4 is a diagram illustrating the color filter 51 according to thefirst embodiment of the present invention. Here, FIG. 4 illustrates theupper surface thereof. As illustrated in FIG. 4, the color filter 51includes a blue filter layer 51B in addition to the green filter layer51G and red filter layer 51R illustrated in FIG. 3. Two or more greenfilter layers 51G, red filter layers 51R, and blue filter layers 51B areeach arrayed so as to correspond to the multiple pixels P arrayed on theimaging region PA. With the present embodiment, such as illustrated inFIG. 4, each of the layers 51R, 51G, and 51B is disposed in a Bayerarray.

Each of the layers 51R, 51G, and 51B is formed by being applied usingcoating liquid containing pigment according to each color, a dispersionresin, a photopolymerization initiator, a multifunctionalphotopolymerization compound, a solvent, and other additives, thendried, and then being subjected to pattern processing by the lithographytechnology.

(9) About the Micro Lens 61

The micro lens 61 is, such as illustrated in FIG. 3, provided above eachlight-receiving surface JS of the multiple photodiodes 21, above thecolor filter 51.

FIGS. 5A, 5B, and 6 are diagrams illustrating the micro lens 61according to the first embodiment of the present invention. Here, FIGS.5A and 5B illustrate the cross-section thereof, and FIG. 6 illustratesthe upper surface thereof. Specifically, FIG. 5A illustrates thecross-section (Y1-Y2 portion) in the vertical direction y illustrated inFIG. 6, and FIG. 5B illustrates the cross-section (K1-K2 portion) in thediagonal direction k illustrated in FIG. 6. Also, the above FIG. 3illustrates the cross-section (X1-X2 portion) in the horizontaldirection x illustrated in FIG. 6.

As illustrated in FIGS. 3 and 5, the micro lens 61 is a convex lensformed with the center being thicker than the edge in the depth-wisedirection z from the light-receiving surface JS toward the color filter51 side, and is configured to focus the incident light H onto the centerof the light-receiving surface JS.

Also, such as illustrated in FIG. 6, multiple micro lenses 61 areprovided in each of the horizontal direction x and the verticaldirection y. The multiple micro lenses 61 are disposed so as tocorrespond to the multiple pixels P arrayed in the imaging region PA,respectively (see FIG. 2). That is to say, the multiple micro lenses 61are disposed in each of the horizontal direction x and the verticaldirection y in the same way as with the multiple photodiodes 21, andmake up a lens array.

As illustrated in FIG. 6, the micro lens 61 is formed so as to have ashape including a portion obtained by the planar shape of the imagingface being divided by a side extending in the horizontal direction x,and a side extending in the vertical direction y. That is to say, eachof the micro lenses 61 is formed so that the planar shape becomes asquare shape.

The multiple micro lenses 61 are, such as illustrated in FIGS. 3 and 6,each disposed so as to be arrayed mutually adjacent to each of thehorizontal direction x and the vertical direction y.

Here, of the multiple micro lenses 61, the micro lenses 61 arrayedadjacent to the horizontal direction x are formed so as to mutually comeinto contact with a side extending in the vertical direction y. Also, ofthe multiple micro lenses 61, the micro lenses 61 arrayed adjacent tothe vertical direction y are formed so as to come into contact with eachother at a side extending in the horizontal direction x, such asillustrated in FIGS. 5A and 6.

The micro lenses 61 arrayed in each of the horizontal direction x andthe vertical direction y are formed so the lens surface becomes the samesuch as illustrated in FIGS. 3 and 5A. Specifically, each of the microlenses 61 is formed so that the curvature of the lens surface becomesthe same in the cross-section in each of the horizontal direction x andthe vertical direction y. Also, each of the micro lenses 61 is formed sothat the depths Dx and Dy of the grooves formed between the micro lenses61 become the same in the cross-section in each of the horizontaldirection x and the vertical direction y.

On the other hand, of the multiple micro lenses 61, the micro lenses 61arrayed adjacent to the diagonal direction k are formed so as to comeinto contact with each other at a portion where a side extending in thehorizontal direction x and a side extending in the vertical direction yintersect, such as illustrated in FIGS. 3 and 5B.

The lens surfaces of the micro lenses 61 arrayed in the diagonaldirection k differ in curvature from the lens surfaces of the microlenses 61 in the horizontal direction x and the vertical direction y,such as illustrated in FIG. 5B. Here, the lens surfaces of the microlenses 61 arrayed in the diagonal direction k are formed so that thecurvature thereof is higher than that of the lens surfaces of the microlenses 61 in the horizontal direction x and the vertical direction y.

Also, the depth Dk of a groove formed between the micro lenses 61arrayed in the diagonal direction k is formed so as to be deeper thanthe depths Dx and Dy of grooves formed between the micro lenses 61arrayed in the horizontal direction x and the vertical direction y. Notethat the depths Dx, Dy, and Dk of the grooves formed between themultiple micro lenses 61 are defined with distance between the lenscenter and the lens edge portion in the depth direction z.

With the above, the depths Dx and Dy of the grooves formed between themicro lenses 61 arrayed in the horizontal direction x are suitably 150nm or less.

In the case of other than this range, focusing to the photodiode 21 isperformed with a high angle, and accordingly, inconvenience ofdeterioration in smear may occur.

Also, with the above, relationship between the depth Dk of the grooveformed between the micro lenses 61 arrayed in the diagonal direction k,and the depth Dx of the groove formed between the micro lenses 61arrayed in the horizontal direction x suitably satisfies the followingExpression (1).

In the event that the Dk is triple or less as to the Dx, sufficientsensitivity is not obtained due to insufficient curvature, and in theevent that the Dk is five times or more, the curvature is too high, andsmear may deteriorate.Dx:Dk=1:3 to 5  (1)

In this way, with the present embodiment, the micro lenses 61 are formedso as to configure an aspherical lens.

B. Manufacturing Method

The manufacturing method for manufacturing the above solid-state imagingdevice 1 will be described.

FIGS. 7 and 8 are diagrams illustrating principal portions provided ateach process of the manufacturing method of the solid-state imagingdevice 1 according to the first embodiment of the present invention. InFIGS. 7 and 8, each process of the manufacturing method of thesolid-state imaging device 1 is illustrated in the sequence of (a), (b),(c), and (d). In FIGS. 7 and 8, the left side portion illustrates, inthe same way as with FIG. 3, a cross-section (X1-X2 portion) in thehorizontal direction x illustrated in FIG. 6. Also, in FIGS. 7 and 8,the right side portion illustrates, in the same way as with FIG. 5B, across-section (K1-K2 portion) in the diagonal direction k illustrated inFIG. 6. The cross-section (Y1-Y2 portion) in the vertical direction yillustrated in FIG. 6 is the same as the left side portion in FIGS. 7and 8, and accordingly, description thereof will be omitted.

(1) Formation of the Color Filter 51

First, such as illustrated in (a) in FIG. 7, the color filter 51 isformed. Here, before formation of the color filter 51, such asillustrated in FIG. 3, the photodiodes 21, charge readout channelregions 22R, charge transfer channel regions 23T, and channel stopperregions 24C are provided to the substrate 101. Subsequently, after thetransfer electrodes 31, metal light-shielding films 41, and intra-layerlenses 45 are each formed on the surface of the substrate 101, aflattening film HT1 is formed. Subsequently, the color filter 51 isformed on the upper surface of the flattening film HT1.

Specifically, such as illustrated in FIG. 4, each of the green filterlayer 51G, red filter layer 51R, and blue filter layer 51B are providedin a manner arrayed with a Bayer array.

For example, coating liquid containing pigment according to each color,a dispersion resin, a photopolymerization initiator, a multifunctionalphotopolymerization compound, a solvent, and other additives is appliedon the flattening film HT1, and is dried. Subsequently, the applied filmis subjected to pattern processing by the lithography technology,thereby sequentially performing formation of each of the layers 51R,51G, and 51B.

(2) Formation of the Lens Material Layer 111 z

Next, such as illustrated in (b) in FIG. 7, formation of a lens materiallayer 111 z will be performed. Here, a polystyrene resin is provided onthe upper surface of the color filter 51 as a lens material layer 111 z.For example, this lens material layer 111 z is formed by the spin coatmethod so that the film thickness becomes 400 μm.

The lens material layer 111 z may be formed using various types ofmaterials, besides a polystyrene resin. For example, the lens materiallayer 111 z may be formed using a material such as an acrylic resin,polyimide resin, epoxy resin, copolymerization resin, or the like.

(3) Formation of the Resist Pattern RP

Next, formation of the resist pattern RP will be performed such asillustrated in (c) in FIG. 8. Here, after coating liquid containing ani-line positive type photosensitive resin such as a novolak resin or thelike is applied on the upper surface of the lens material layer 111 z,the coating liquid is dried, thereby providing a photoresist film (notillustrated). Subsequently, this photoresist film is subjected topattern processing using photolithography technology, thereby forming aresist pattern RP on the upper surface of the lens material layer 111 z.That is to say, after exposure processing is carried out wherein themask pattern image of a photo mask (not illustrated) is transferred tothe photoresist film, the photoresist film subjected to the exposureprocessing is subjected to development, thereby forming a resist patternRP. Thus, the resist pattern RP protruding at the upper surface of thelens material layer 111 z is formed.

Specifically, such as illustrated in (c) in FIG. 8, the resist patternRP is formed so that the center portion of a region where the microlenses 61 illustrated in FIGS. 3, 5A, and 5B are formed has filmthickness thicker than around the center portion thereof.

With the present embodiment, such as illustrated on the left and rightsides in (c) in FIG. 8, the resist pattern RP is formed so that thethickness around the center portion of the region where the micro lens61 (see FIGS. 3, 5A, and 5B) is formed differs between the horizontaldirection x and the diagonal direction k. Here, the resist pattern RP isformed so that film thickness Mx in the horizontal direction x isthicker than thickness Mk in the diagonal direction k.

For example, with the circumference of the center portion of the regionwhere the micro lenses 61 (see FIGS. 3, 5A, and 5B) are formed, the filmthickness Mk in the diagonal direction k (the right side portion in (c)in FIG. 8) is 0, and the thickness Mx in the horizontal direction x isthicker than the film thickness Mk. In (c) in FIG. 8, though notillustrated in the drawing, formation of the resist pattern RP is alsoperformed so that film thickness My in the vertical direction y becomesthe same thickness as the film thickness Mx in the horizontal directionx (i.e., Mx=My).

FIG. 9 is a diagram illustrating a photo mask to be used for theformation process of the resist pattern RP according to the firstembodiment of the present invention. FIG. 9 illustrates the uppersurface thereof.

As illustrated in FIG. 9, with a portion where the resist pattern RP isformed while remaining the photoresist film, a photo mask PM is employedwherein a light-shielding portion SK for shielding exposing light in theexposure processing is provided as a mask pattern.

On the other hand, such as illustrated in FIG. 9, with regard to aboundary portion between the micro lenses 61 (see FIG. 6) arrayed in thehorizontal direction x and the vertical direction y, in order to remaina part of the photoresist film, a semi-transmissive portion FT of ahalftone mask is provided. Also, such as illustrated in FIG. 9, withregard to a portion between the micro lenses 61 (see FIG. 6) formedarrayed in the diagonal direction k, in order to remove the wholeportion of the photoresist film, a transmissive portion TT is provided.

After the exposure processing is carried out regarding the photoresistfilm using the above photo mask PM, the development is performed,thereby forming the resist pattern RP so that the film thicknesses Mxand My in the horizontal direction x and the vertical direction y arethicker than the film thickness Mk in the diagonal direction k.

For example, formation of the resist pattern RP is carried out inaccordance with the following conditions.

Resist Pattern RP Forming Conditions

Photoresist material: i-line positive type resist

Photoresist film thickness: 400 nm

Prebaking conditions: 80° C. 90 sec. (on a hot plate)

Exposure conditions: ¼ reduction exposure device (NA 0.5, σ0.7)

Baking conditions after exposure: none

Developing conditions: developer TMAH 2.38%, developing time 60 sec x 2puddle development

Note that description has been made above regarding a case whereexposure processing is carried out using a halftone mask, but thepresent embodiment is not restricted to this. For example, underexposing (0.3 μm or more) may be allowed using a photo mask wherein alinewidth pattern of an i-line resolution level is formed. Also, theabove exposure processing may be carried out using a photo mask whereina linewidth pattern equal to or smaller than i-line resolution isformed.

(4) Resist Pattern RP is Processed into a Lens Shape

Next, the resist pattern RP is processed into a lens shape such asillustrated in (d) in FIG. 8. Here, the resist pattern RP thus formed issubjected to a heating reflow process, thereby processing the resistpattern RP into a lens shape.

In a heating reflow process step according to the present embodiment,the heating reflow process is carried out so that the resist patternsarrayed adjacent to the diagonal direction k on the imaging face hold astate separated between the resist patterns, and also the resistpatterns arrayed in the horizontal direction x are mutually fused.

Specifically, for example, post bake processing is carried out twice asthe heating reflow process. For example, the heating reflow process iscarried out so that the temperature condition of the second post bakeprocessing to be carried out second time is higher than the temperaturecondition of the first post bake processing to be carried out firsttime.

For example, the present process is carried out under the followingreflow process conditions.

First post bake processing conditions: 140 through 150° C., 120 sec. (ona hot plate)

Second post bake processing conditions: 170 through 180° C., 120 sec.(on a hot plate)

Thus, such as illustrated in (d) in FIG. 8, the surface becomes a curvedsurface, and the resist pattern RP is processed into a lens shape.

With the present embodiment, such as illustrated in the left sideportion in (d) in FIG. 8, a boundary portion between the micro lenses 61(see FIGS. 3, 5A, and 5B) arrayed in the horizontal direction x isformed so that the lens-shaped resist patterns RP are formed so as to bemutually fused. Though not illustrated in the drawing, even with theboundary line portion between the micro lenses 61 arrayed in thevertical direction y, the lens-shaped resist patterns RP are formed soas to be mutually fused. That is to say, with this portion, thelens-shaped resist patterns RP are formed so that the lens basedmaterial film 111 z is covered.

On the other hand, such as illustrated in the right side portion in (d)in FIG. 8, a portion between the micro lenses 61 (see FIGS. 3, 5A, and5B) arrayed in the diagonal direction k is formed so that thelens-shaped resist patterns RP are formed in a state separated betweenthe resist patterns. That is to say, with this portion, the lens-shapedresist patterns RP are formed so that the surface of the lens materiallayer 111 z is exposed.

Therefore, such as illustrated in FIG. 8, the lens-shaped resistpatterns RP are formed so that the film thickness of a portion betweenthe multiple micro lenses 61 is thicker in the diagonal direction k thanin the horizontal direction x and the vertical direction y. Further, thelens-shaped resist patterns RP are fused in the horizontal direction xand the vertical direction y, and accordingly, the lens-shaped resistpatterns RP are formed so that the curvature is lower in the diagonaldirection k than the horizontal direction x and the vertical directiony. That is to say, the resist patterns RP are formed in a lens shape soas to correspond to the curvature of the lens surface of the micro lens61 to be formed.

(5) Formation of the Micro Lens 61

Next, formation of the micro lens 61 is performed such as illustrated inFIGS. 3, 5A, 5B, and 6. Here, the lens-shaped resist pattern RP isemployed as a mask, and the whole surface of the lens material layer 111z is subjected to an etchback process. That is to say, the lens materiallayer 111 z is processed into micro lenses 61 so that the lens-shapedpattern of the resist pattern RP is transferred to the lens materiallayer 111 z.

Thus, the resist pattern RP and the lens material layer 111 z areremoved, and the lens material layer 111 z is pattern-processed intomicro lenses 61 such as illustrated in FIGS. 3, 5A, 5B, and 6.

With the present embodiment, such as illustrated in FIGS. 3 and 6, eachof the micro lenses 61 is formed so that the micro lenses 61 arrayedadjacent to the horizontal direction x come into contact with each otherat a side extending in the vertical direction y. Also, such asillustrated in FIGS. 5A and 6, each of the micro lenses 61 is formed sothat the micro lenses 61 arrayed adjacent to the vertical direction ycome into contact with each other at a side extending in the horizontaldirection x. Further, each of the micro lenses 61 is formed so that thelens surfaces of the micro lenses 61 have the same curvature at eachcross-section in the horizontal direction x and the vertical directiony, and the depths Dx and Dy of grooves between the micro lenses 61 havethe same depth.

Also, such as illustrated in FIGS. 3 and 5B, each of the micro lenses 61is formed so that the micro lenses 61 arrayed adjacent to the diagonaldirection k come into contact with each other at a portion where a sideextending in the horizontal direction x and a side extending in thevertical direction y intersect. Subsequently, each of the micro lenses61 is formed so that the lens surfaces of the micro lenses 61 arrayed inthe diagonal direction k have higher curvature than the lens surfaces ofthe micro lenses 61 in the horizontal direction x and the verticaldirection y. Further, each of the micro lenses 61 is formed so that thedepth Dk of a groove to be formed between the micro lenses 61 arrayed inthe diagonal direction k is deeper than the depths Dx and Dy of groovesto be formed between the micro lenses 61 arrayed in the horizontaldirection x and the vertical direction y.

For example, the above etchback process is carried out under thefollowing conditions to form each of the micro lenses 61.

Etching Conditions

Etchback device: magnetron RIE device

Etching gas: CF4=155 ccm

High-frequency power: 1.8 W/cm2

Pressure within an etching room: 6.65 Pa

Lower electrode temperature (chiller temperature): 0° C.

Etching amount: 2.4 μm (converted into terms of stainless steel resist)

Thus, each of the micro lenses 61 is formed so that the depth Dx of agroove to be formed between the micro lenses 61 arrayed in thehorizontal direction x is equal to or less than 150 nm. Also, each ofthe micro lenses 61 is formed so that relationship between the depth Dkof a groove to be formed between the micro lenses 61 arrayed in thediagonal direction k, and the depth Dx of a groove to be formed betweenthe micro lenses 61 arrayed in the horizontal direction x satisfies theabove Expression (1). That is to say, each of the micro lenses 61 isformed as an aspherical lens.

Note that various types of etchback device other than a magnetron RIEdevice may be employed as an etchback device. For example, the followingetchback devices may be employed.

Parallel plate type RIE device

High-pressure narrow gap type plasma etching device

ECR type etching device

Microwave plasma type etching device

Transformer-coupling plasma type etching device

Inductively-coupled-plasma type etching device

Helicon-wave-plasma type etching device

C. Conclusion

As described above, with the present embodiment, the micro lenses 61 ofwhich the planar shape of the imaging face has a shape including aportion divided by a side extending in the horizontal direction x, and aside extending in the vertical direction y. The multiple micro lenses 61are disposed so as to be arrayed adjacent to each other in each of thehorizontal direction x and the vertical direction y. Also, the multiplemicro lenses 61 are formed so that the depth of a groove between themicro lenses 61 arrayed in the diagonal direction k inclined as to thehorizontal direction x and the vertical direction y of the image surfaceis deeper than the depth of a groove between the micro lenses 61 arrayedin the horizontal direction x. Further, the multiple micro lenses arealso formed so that the curvature of the lens surface in the diagonaldirection k is higher than the curvature of the lens surface in thehorizontal direction x.

Also, the multiple micro lenses 61 are formed so that depth D1 of agroove between the micro lenses 61 arrayed in the horizontal directionx, and depth D3 of a groove between the micro lenses arrayed in thediagonal direction k have a relation of D1:D3=1:3 to 5.

Also, the multiple micro lenses 61 are formed so that depth D1 of agroove between the micro lenses 61 arrayed in the horizontal direction xhas a relation of D1≤150 nm.

As described above, in the event that the curvature of the micro lenses61 is high (in the event that the lens layer thickness is thick), thesensitivity thereof is generally improved. CCD-type solid-state imagingdevices have features wherein the sensor shape is a square shape such asa square, rectangle, or the like, and accordingly, smear readily occursin the horizontal direction x, but smear is prevented from occurring inthe diagonal direction k.

With the present embodiment, the micro lenses 61 have features whereinthe curvature in the diagonal direction k is higher than the curvaturein the horizontal direction x, and accordingly, incident light from thediagonal direction k where smear is prevented from occurring caneffectively be focused onto the light-receiving surface. That is to say,the curvature of the micro lenses 61 is low in the horizontal directionx (lens thickness is thin), and accordingly, input of light to thevertical transfer unit serving as a cause for occurrence of smear can beprevented. Also, the curvature of the micro lenses 61 is high in thediagonal direction k (lens thickness is thick), the sensitivity can beimproved. Thus, the present embodiment can effectively realize both ofimprovement in sensitivity, and prevention of occurrence of smear.

Specifically, with the solid-state imaging device according to thepresent embodiment, it has been confirmed that the sensitivity improves4%, and also the smear improves 0.4 dB as to the configuration accordingto the related art.

Accordingly, with the present embodiment, the micro lenses 61 are formedwith high precision, whereby focusing efficiency can be improved, andthe image quality of an imaged image can readily be improved.

2. Second Embodiment A. Device Configuration, Etc.

FIG. 10 is a diagram illustrating the principal portions of asolid-state imaging device according to a second embodiment of thepresent invention. Here, FIG. 10 illustrates a portion where the microlenses 61 are formed, and illustrates a cross-section (Y1-Y2 portion) inthe vertical direction y, in the same way as FIG. 5A.

As illustrated in FIG. 10, with the present embodiment, the micro lenses61 differ from those according to the first embodiment. Except for thisand related points, the present embodiment is the same as the firstembodiment, so description of redundant portions will be omitted.

With the first embodiment, each of the micro lenses 61 is formed so thatthe curvature of the lens surface is the same at the cross-section ineach of the horizontal direction x and the vertical direction y. Also,each of the micro lenses 61 is formed so that the depths Dx and Dy ofgrooves to be formed between the micro lenses 61 are the same at thecross-section in each of the horizontal direction x and the verticaldirection y.

However, with the present embodiment, such as illustrated in FIG. 10,each of the micro lenses 61 is formed so that the curvature of the lenssurface at the cross-section in each of the horizontal direction x andthe vertical direction y mutually differs. Also, each of the microlenses 61 is formed so that the depth Dx and Dy of grooves to be formedbetween the micro lenses 61 mutually differ at the cross-section in eachof the horizontal direction x and the vertical direction y.

Specifically, each of the micro lenses 61 is formed so that thecurvature of the lens surface on a cross-section in the verticaldirection y is higher than the curvature of the lens surface at thecross-section in the horizontal direction x. Also, each of the microlenses 61 is formed so that the depth Dy of a groove between the microlenses 61 at the cross-section in the vertical direction y is deeperthan the depth Dx of a groove between the micro lenses 61 at thecross-section in the horizontal direction x.

Note that each of the micro lenses 61 is formed in the same way as withthe first embodiment regarding the cross-section in the diagonaldirection k.

B. Manufacturing Method

Description will be made regarding the manufacturing method formanufacturing the solid-state imaging device according to the presentembodiment.

FIG. 11 is a diagram illustrating principal portions to be provided ateach process of the manufacturing method of the solid-state imagingdevice according to the second embodiment of the present invention. FIG.11 illustrates each process of the manufacturing method of thesolid-state imaging device in the sequence of (a) and (b). In FIG. 11,the left side portion illustrates, in the same way as FIG. 3, thecross-section (X1-X2 portion) in the horizontal direction x illustratedin FIG. 6. Also, in FIG. 11, the right side portion illustrates, in thesame way as FIG. 5B, the cross-section (K1-K2 portion) in the diagonaldirection k illustrated in FIG. 6. Further, in FIG. 11, the centralportion illustrates, in the same way as FIG. 10, the cross-section(Y1-Y2 portion) in the vertical direction y illustrated in FIG. 6.

(1) Formation of the Resist Pattern RP

First, such as illustrated in (a) in FIG. 11, formation of the resistpattern RP is performed. Here, before formation of the resist patternRP, in the same way as with the first embodiment, formation of the colorfilter 51, and formation of the lens material layer 111 z are carriedout in this order.

Subsequently, in the same way as with the first embodiment, after aphotoresist film (not illustrated) is provided to the upper face of thelens material layer 111 z, processing for subjecting the photoresistfilm thereof to pattern processing is carried out to generate the resistpattern RP.

With the present embodiment, such as illustrated on the left side andthe right side in (a) in FIG. 11, the resist pattern RP is formedregarding each cross-section in the horizontal direction x and thediagonal direction k in the same way as with the first embodiment.

However, such as illustrated in the central portion in (a) in FIG. 11,the resist pattern RP is formed regarding the cross-section in thevertical direction y so as to be different from the first embodiment.

Specifically, such as illustrated in (a) in FIG. 11, the resist patternRP is formed so that the film thickness around the center portion of aregion where the micro lenses 61 (see FIGS. 3, 5A, and 5B) are formedmutually differs between the horizontal direction x and the verticaldirection y. Here, formation is performed so that the film thickness Myin the vertical direction y is thinner than the film thickness Mx in thehorizontal direction x.

For example, in the same way as the cross-section in the diagonaldirection k, the resist pattern RP is formed so that the surface of thelens material layer 111 z is exposed at the boundary portion of aportion where the micro lenses 61 (see FIGS. 3, 5A, and 5B).

FIG. 12 is a diagram illustrating a photo mask to be used for theformation process of the resist pattern RP according to the secondembodiment of the present invention. FIG. 12 illustrates the uppersurface thereof. As illustrated in FIG. 12, in the same way as with thefirst embodiment, a light-shielding portion SK for shielding exposinglight is provided to a portion where the resist pattern RP is formedwhile remaining a photoresist film, as a mask pattern. Also, with regardto a boundary portion between the micro lenses 61 (see FIG. 6) arrayedin the horizontal direction x, in order to remain a part of thephotoresist film, a semi-transmissive portion FT of a halftone mask isprovided.

However, with the present embodiment, unlike the first embodiment, withregard to a portion between the micro lenses 61 (see FIG. 6) arrayed inthe vertical direction y and the diagonal direction k, in order toremove the whole of the photoresist film, a photo mask PM to which atransmissive portion TT is provided is employed.

Subsequently, after the photoresist film is subjected to the exposureprocessing using the above photo mask PM, development is carried out,and accordingly, the above resist pattern RP is formed.

Note that description has been made above regarding a case where theexposure processing is carried out using the halftone mask, but thepresent embodiment is not restricted to this. In the same way as withthe first embodiment, for example, under exposing (0.3 μm or more) maybe allowed using a photo mask wherein a linewidth pattern of an i-lineresolution level is formed. Also, the above exposure processing may becarried out using a photo mask wherein a linewidth pattern equal to orsmaller than i-line resolution is formed.

(2) Resist Pattern RP is Processed into a Lens Shape

Next, the resist pattern RP is processed into a lens shape such asillustrated in (b) in FIG. 11. Here, in the same way as with the firstembodiment, the resist pattern RP thus formed is subjected to theheating reflow process, thereby processing the resist pattern RP into alens shape.

With the present embodiment, such as illustrated in the left sideportion in (b) in FIG. 11, a boundary portion between the micro lenses61 (see FIGS. 3, 5A, and 5B) arrayed in the horizontal direction x isformed so that the lens-shaped resist patterns RP are mutually fused inthe same way as with the first embodiment. That is to say, thelens-shaped resist patterns RP are formed so as to cover the lensmaterial layer 111 z at this portion.

Also, such as illustrated in the right side portion in (b) in FIG. 11,with a portion between the micro lenses 61 (see FIGS. 3, 5A, and 5B)arrayed in the diagonal direction k, in the same way as the firstembodiment, the lens-shaped resist patterns RP are formed so as to beseparated therebetween. That is to say, the lens-shaped resist patternsRP are formed so that the surface of the lens material layer 111 z isexposed at this portion.

On the other hand, such as illustrated in the central portion in (b) inFIG. 11, with a boundary portion between the micro lenses 61 (see FIG.10) arrayed in the vertical direction y, unlike the first embodiment,the lens-shaped resist patterns RP are formed so as to be separatedtherebetween. That is to say, with this portion, the lens-shaped resistpatterns RP are formed so that the surface of the lens material layer111 z is exposed.

Therefore, such as illustrated in FIG. 11, the lens-shaped resistpatterns RP are formed so that the film thickness of a portion betweenthe multiple micro lenses 61 is thicker in the vertical direction y andthe diagonal direction k than in the horizontal direction x. Further,the lens-shaped resist patterns RP are fused in the horizontal directionx, and accordingly, each of the lens-shaped resist patterns RP is formedso that the curvature is lower in the vertical direction y and thediagonal direction k than the horizontal direction x. That is to say,the resist pattern RP is formed in a lens shape so as to correspond tothe curvature of the lens surface of the micro lens 61 to be formed.

(3) Formation of the Micro Lens 61

Next, formation of the micro lens 61 is performed such as illustrated inFIGS. 3, 5B, and 10. Here, in the same way as with the first embodiment,the lens-shaped resist pattern RP is employed as a mask, and the wholesurface of the lens material layer 111 z is subjected to the etchbackprocess. That is to say, the lens material layer 111 z is processed intomicro lenses 61 so that the lens-shaped pattern of the resist pattern RPis transferred to the lens material layer 111 z.

With the present embodiment, unlike the first embodiment, each of themicro lenses 61 is formed so that the curvature of the lens surface atthe cross-section in the vertical direction y is higher than thecurvature of the lens surface at the cross-section in the horizontaldirection x. Also, each of the micro lenses 61 is formed so that thedepth Dy of a groove between the micro lenses 61 at the cross-section inthe vertical direction y is deeper than the depth Dx of a groove betweenthe micro lenses 61 at the cross-section in the horizontal direction x.

C. Conclusion

As described above, with the present embodiment, in the same way as thefirst embodiment, the multiple micro lenses 61 are formed so that thedepth of a groove between the micro lenses 61 arrayed in the diagonaldirection k of the image surface is deeper than the depth of a groovebetween the micro lenses 61 arrayed in the horizontal direction x. Also,the multiple micro lenses 61 are formed so that the curvature of thelens surface in the diagonal direction k is higher than the curvature ofthe lens surface in the horizontal direction x.

With the present embodiment, with the micro lenses 61, in the same wayas with the first embodiment, the curvature of the micro lenses 61 islow in the horizontal direction x (lens thickness is thin), wherebyinput of light to the vertical transfer unit serving as a cause ofoccurrence of smear can be prevented.

Also, with the present embodiment, the multiple micro lenses 61 areformed so that the depth of a groove between the micro lenses 61 arrayedin the vertical direction y is deeper than the depth of a groove betweenthe micro lenses 61 arrayed in the horizontal direction x. Further, themultiple micro lenses 61 are formed so that the curvature of the lenssurface in the vertical direction y is higher than the curvature of thelens surface in the horizontal direction x. Thus, with the presentembodiment, the curvature of the micro lenses 61 is higher (lensthickness is thicker) in the vertical direction y than the horizontaldirection x in the same way as with the diagonal direction k, andaccordingly, the sensitivity can further be improved. Therefore, thepresent embodiment can effectively realize both of improvement insensitivity, and prevention of occurrence of smear.

Accordingly, with the present embodiment, the micro lenses 61 are formedwith high precision, whereby focusing efficiency can be improved, andthe image quality of an imaged image can readily be improved.

3. Third Embodiment A. Device Configuration, Etc.

FIGS. 13A and 13B are diagrams illustrating the principal portions of asolid-state imaging device according to a third embodiment of thepresent invention. Here, FIGS. 13A and 13B illustrate a portion wherethe micro lenses 61 are formed, where FIG. 13A illustrates across-section (X1-X2 portion) in the horizontal direction x, and FIG.13B illustrates a cross-section (Y1-Y2 portion) in the verticaldirection y.

As illustrated in FIGS. 13A and 13B, with the present embodiment, themicro lenses 61 differ from those according to the first embodiment.Other than this and related points, the present embodiment is the sameas the first embodiment, so description of redundant portions will beomitted.

As illustrated in FIG. 13A, at the cross-section in the horizontaldirection x, the micro lenses 61 are provided so that the upper surfaceportion is along the horizontal direction x.

On the other hand, at the cross-section in the vertical direction y, themicro lenses 61 are configured as a convex lens wherein the uppersurface portion is a curved surface, and the center is formed so as tobe thicker than the edge.

That is to say, with the present embodiment, the micro lenses 61 areformed so that the cross-section in the vertical direction y has a lensshape, and the cross-section in the horizontal direction x has adome-like shape extending linearly.

B. Manufacturing Method

Description will be made regarding the manufacturing method formanufacturing the solid-state imaging device according to the presentembodiment.

FIG. 14 is a diagram illustrating principal portions to be provided ateach process of the manufacturing method of the solid-state imagingdevice according to the third embodiment of the present invention. FIG.14 illustrates each process of the manufacturing method of thesolid-state imaging device in the sequence of (a) and (b). In FIG. 14,the left side portion illustrates, in the same way as FIG. 13A, thecross-section (X1-X2 portion) in the horizontal direction x. Also, inFIG. 14, the right side portion illustrates, in the same way as FIG.13B, the cross-section (Y1-Y2 portion) in the vertical direction y.

(1) Formation of the Resist Pattern RP

First, such as illustrated in (a) in FIG. 14, formation of the resistpattern RP will be performed. Here, before formation of the resistpattern RP, in the same way as with the first embodiment, formation ofthe color filter 51, and formation of the lens material layer 111 z arecarried out in this order.

Subsequently, in the same way as with the first embodiment, after aphotoresist film (not illustrated) is provided to the upper face of thelens material layer 111 z, processing for subjecting the photoresistfilm thereof to pattern processing is carried out to generate the resistpattern RP. Specifically, after exposure processing is carried outwherein a pattern image is exposed to the photoresist film, developmentis carried out, thereby forming the resist pattern RP.

With the present embodiment, such as illustrated on the left side in (a)in FIG. 14, with regard to the cross-section in the horizontal directionx, the resist pattern RP is formed so that a state flatly extending tothe horizontal direction x is maintained without providing an openingportion.

On the other hand, such as illustrated on the right side in (a) in FIG.14, with regard to the cross-section in the vertical direction y, theresist pattern RP is formed so that a portion between the micro lenses61 being formed is opened. That is to say, with regard to this portion,the resist pattern RP is formed so that the surface of the lens materiallayer 111 z is exposed.

(2) Resist Pattern RP is Processed into a Lens Shape

Next, the resist pattern RP is processed into a lens shape such asillustrated in (b) in FIG. 14. Here, in the same way as with the firstembodiment, the resist pattern RP thus formed is subjected to theheating reflow process, thereby processing the resist pattern RP into alens shape.

With the present embodiment, such as illustrated in the left sideportion in (b) in FIG. 14, with regard to the cross-section in thehorizontal direction x, no opening portion is provided, and accordingly,a state flatly extending to the horizontal direction x is maintained.

On the other hand, such as illustrated on the right side in (b) in FIG.14, with regard to the cross-section in the vertical direction y, theportion between the micro lenses 61 being formed is opened, andaccordingly, the resist patterns RP are fused and processed into a lensshape.

(3) Formation of the Micro Lens 61

Next, formation of the micro lens 61 is performed such as illustrated inFIGS. 13A and 13B. Here, in the same way as with the first embodiment,the lens-shaped resist pattern RP is employed as a mask, and the wholesurface of the lens material layer 111 z is subjected to the etchbackprocess. That is to say, the lens material layer 111 z is processed intomicro lenses 61 so that the lens-shaped pattern of the resist pattern RPis transferred to the lens material layer 111 z.

With the present embodiment, unlike the first embodiment, each of themicro lenses 61 is formed so that the cross-section in the verticaldirection y has a lens shape, and the cross-section in the horizontaldirection x has a dome-like shape extending linearly.

C. Conclusion

As described above, with the present embodiment, the micro lenses 61 areformed so that the lens surface to which the incident light H is inputis a curved surface in the vertical direction y, and is flat in thehorizontal direction x. That is to say, such as described above, thelens surface is formed in a dome-like shape.

With the present embodiment, with the micro lenses 61, the upper surfaceis flat in the horizontal direction x, and accordingly, in the same wayas with the first embodiment, the curvature of the lens surface is low,whereby input of light to the vertical transfer unit serving as a causeof occurrence of smear can be prevented. Also, in the vertical directiony, the curvature of the lens surface is high, and focusing efficiency ishigh, and accordingly, sensitivity can be improved. Therefore, thepresent embodiment can effectively realize both of improvement insensitivity, and prevention of occurrence of smear.

Accordingly, with the present embodiment, the image quality of an imagedimage can readily be improved.

4. Fourth Embodiment A. Device Configuration, Etc.

A-1. Principal Portion Configuration of Solid-State Imaging Device

FIG. 15 is a diagram illustrating the principal portions of asolid-state imaging device according to a fourth embodiment of thepresent invention. The solid-state imaging device according to thepresent embodiment is a CMOS-type image sensor, which differs from thataccording to the first embodiment. Other than this and related points,the present embodiment is the same as the first embodiment, sodescription of redundant portions will be omitted.

As illustrated in FIG. 15, the solid-state imaging device according tothe present embodiment includes a substrate 101. This substrate 101 is,for example, a semiconductor substrate made up of silicon, and animaging region PA and a peripheral region SA are provided to the surfaceof the substrate 101.

The imaging region PA has, such as illustrated in FIG. 15, a rectangularshape where multiple pixels P are disposed in each of the horizontaldirection x and the vertical direction y. That is to say, the pixels Pare arrayed in a matrix shape. With the imaging region PA, the centerthereof is disposed so as to correspond to the optical axis of theoptical system 42 illustrated in FIG. 1. Note that the imaging region PAis equivalent to the imaging face PS illustrated in FIG. 1.

With the imaging region PA, the pixels P receive incident light togenerate signal charge. Subsequently, the generated signal chargethereof is read out and output by a pixel transistor. The detailedconfiguration of the pixels P will be described later.

The peripheral region SA is, such as illustrated in FIG. 15, locatedaround the imaging region PA. With this peripheral region SA, peripheralcircuits are provided.

Specifically, such as illustrated in FIG. 15, a vertical driving circuit13, a column circuit 14, a horizontal driving circuit 15, an externaloutput circuit 17, a timing generator (TG) 18, and a shutter drivingcircuit 19 are provided as a peripheral circuit.

The vertical driving circuit 13 is, such as illustrated in FIG. 15, inthe peripheral region SA, provided lateral to the imaging region PA, andis configured to select the pixels P of the imaging region PA inincrements of rows to drive these.

The column circuit 14 is, such as illustrated in FIG. 15, in theperipheral region SA, provided in the lower edge portion of the imagingregion PA, and carries out signal processing regarding the signal to beoutput from the pixels P in increments of columns. Here, the columncircuit 14 includes a CDS (Correlated Double Sampling) circuit (notillustrated), and carries out signal processing for removing fixedpattern noise.

The horizontal driving circuit 15 is, such as illustrated in FIG. 15,electrically connected to the column circuit 14. The horizontal drivingcircuit 15 includes, for example, a shift resistor, which sequentiallyoutputs a signal held for each column of the pixels P in the columncircuit 14 to the external output circuit 17.

The external output circuit 17 is, such as illustrated in FIG. 15,electrically connected to the column circuit 14, and after the signalprocessing is carried out regarding the signal to be output from thecolumn circuit 14, externally outputs this. The external output circuit17 includes an AGC (Automatic Gain Control) circuit 17 a, and an ADCcircuit 17 b. With the external output circuit 17, after the AGC circuit17 a applies gain to the signal, the ADC circuit 17 b converts theanalog signal to a digital signal, and externally outputs this.

The timing generator 18 is, such as illustrated in FIG. 15, electricallyconnected to each of the vertical driving circuit 13, column circuit 14,horizontal driving circuit 15, external output circuit 17, and shutterdriving circuit 19. The timing generator 18 generates various types oftiming signal to output this to the vertical driving circuit 13, columncircuit 14, horizontal driving circuit 15, external output circuit 17,and shutter driving circuit 19, thereby performing driving controlregarding each of the units.

The shutter driving circuit 19 is configured to select the pixels P inincrements of rows to adjust exposure time at the pixels P.

A-2. Detailed Configuration of Solid-State Imaging Device

Description will be made regarding the detailed content of thesolid-state imaging device according to the present embodiment. FIGS. 16and 17 are diagrams illustrating the principal portions of a solid-stateimaging device according to the fourth embodiment of the presentinvention. Here, FIG. 16 illustrates the upper surface of the imagingregion PA, and FIG. 17 illustrates the circuit configuration of thepixels P provided to the imaging region PA.

As illustrated in FIGS. 16 and 17, the solid-state imaging device 1includes a photodiode 21, and a pixel transistor PTr. Here, the pixeltransistor PTr includes, such as illustrated in FIG. 17, a transfertransistor 22, an amplification transistor 23, a selecting transistor24, and a reset transistor 25, and is configured to read out signalcharge from the photodiode 21. Each unit making up the solid-stateimaging device will be described in order.

(1) About the Photodiode 21

With the solid-state imaging device 1, such as illustrated in FIG. 16,the multiple photodiodes 21 are disposed so as to correspond to themultiple pixels P, respectively. The multiple photodiodes 21 aredisposed so as to be arrayed in each of the horizontal direction x, andthe vertical direction y orthogonal to the horizontal direction x, ofthe imaging face (x-y face).

Each of the photodiodes 21 is configured to receive incident light(subject image) to generate signal charge by subjecting the incidentlight to photoelectric conversion, and to accumulate this. For example,each or the photodiodes 21 is configured by an n-type chargeaccumulation region being formed in a p-type semiconductor regionprovided within the substrate 101 that is an n-type siliconsemiconductor. Subsequently, each of the photodiodes 21 is, such asillustrated in FIG. 17, configured so that the accumulated signal chargethereof is read out by the transfer transistor 22, and is transferred tothe drain FD.

With the present embodiment, such as illustrated in FIGS. 16 and 17, atransfer transistor 22 is provided to each of the photodiodes 21 inpairs. For example, four transfer transistors 22 (22A_1, 22A_2, 22B_1,and 22B_2) are provided in pairs so as to correspond to four photodiodes21 (21A_1, 21A_2, 21B_1, and 21B_2).

As illustrated in FIGS. 16 and 17, the multiple photodiodes 21 areconfigured so as to share the single readout drain FD. With the presentembodiment, such as illustrated in FIG. 16, two photodiodes 21 (21A_1and 21A_2, or 21B_1 and 21B_2) arrayed in the diagonal direction k areprovided so as to share the single readout drain FD (FDA or FDB).

As illustrated in FIGS. 16 and 17, a set made up of the multiplephotodiodes 21 is configured so as to share the amplification transistor23, selecting transistor 24, and reset transistor 25 with multiple sets.For example, such as illustrated in FIG. 17, each of the amplificationtransistor 23, selecting transistor 24, and reset transistor 25 isprovided to one set made up of four photodiodes 21 (21A_1, 21A_2, 21B_1,and 21B_2).

(2) About the Pixel Transistor PTr

With the solid-state imaging device 1, the pixel transistor PTr isprovided between the multiple pixels P of the imaging face (x-y face),as shown in FIG. 16. With each of the pixel transistors PTr, anactivated region (not illustrated) is formed in a region separating themultiple pixels P of the substrate 101, and each of the gate electrodesis formed, for example, with polysilicon.

With the pixel transistor PTr, the multiple transistors 22 are formed soas to correspond to each of the multiple pixels P such as illustrated inFIGS. 16 and 17.

Here, such as illustrated in FIG. 16, with the transfer transistors 22,a transfer gate is provided to the surface of the substrate 101 via agate insulating film. With the transfer transistors 22, the transfergate is provided adjacent to a readout drain FD (Floating Diffusion)provided to the surface of the substrate 101.

As illustrated in FIG. 17, the transfer transistors 22 are configured tooutput the signal charge generated at the photodiode 21 to the gate ofthe amplification transistor 23 as an electric signal. Specifically, inthe event that a transfer signal has been given to the gate from atransfer line 26, the transfer transistor 22 transfers the signal chargeaccumulated at the photodiode 21 to the readout drain FD as an outputsignal.

With the present embodiment, such as illustrated in FIG. 16, thetransfer transistors 22 are provided corresponding to the photodiodes21, respectively. For example, such as illustrated in FIG. 16, each ofthe transfer transistors 22 is formed so that two transfer transistors22 sandwich the readout drain FD provided between the multiple pixels Parrayed in the diagonal direction k inclined as to the horizontaldirection x and the vertical direction y of the imaging face (x-y face).

Specifically, such as illustrated in FIG. 16, two transfer transistors22A_1 and 22A_2 are provided so as to sandwich a readout drain FDAprovided between two photodiodes 21A_1 and 21A_2 arrayed in the inclineddirection. Also, two transfer transistors 22B_1 and 22B_2 are providedso as to sandwich a readout drain FDB provided between two photodiodes21B_1 and 21B_2 arrayed in the inclined direction.

With the pixel transistor PTr, the amplification transistor 23 is, suchas illustrated in FIG. 17, configured to amplify and output the electricsignal output from the transfer transistor 22.

Specifically, with the amplification transistor 23, the gate isconnected to the readout drain FD. Also, with the amplificationtransistor 23, the drain is connected to a power-supply potential supplyline Vdd, and the source is connected to the selecting transistor 24. Inthe event that the selecting transistor 24 has been selected so as to bean on state, constant current is supplied from a constant current source(not illustrated), the amplification transistor 23 serves as a sourcefollower. Therefore, with the amplification transistor 23, the outputsignal output from the readout drain FD is amplified by a selectingsignal being supplied to the to the selecting transistor 24.

With the pixel transistor PTr, such as illustrated in FIG. 17, in theevent that the selecting signal has been input, the selecting transistor24 is configured to output the electric signal output by theamplification transistor 23 to a vertical signal line 27.

Specifically, with the selecting transistor 24, such as illustrated inFIG. 17, the gate is connected to an address line 28 to which theselecting signal is supplied. In the event that the selecting signal hasbeen supplied, the selecting transistor 24 goes on, and outputs theoutput signal amplified as described above by the amplificationtransistor 23 to the vertical signal line 27.

With the pixel transistor PTr, the reset transistor 25 is, such asillustrated in FIG. 17, configured to reset the gate potential of theamplification transistor 23.

Specifically, with the reset transistor 25, such as illustrated in FIG.17, the gate is connected to a reset line 29 to which the reset signalis supplied. Also, with the reset transistor 25, the drain is connectedto the power-supply potential supply line Vdd, and the source isconnected to the readout drain FD. In the event that the reset signalhas been supplied to the gate from the reset line 29, the resettransistor 25 resets the gate potential of the amplification transistor23 to power-supply potential via the readout drain FD.

With the present embodiment, each of the above amplification transistors23, selecting transistor 24, and reset transistor 25 is, such asillustrated in FIG. 16, configured to be shared by a set made up of themultiple photodiodes 21.

For example, such as illustrated in FIG. 16, each of the amplificationtransistor 23, selecting transistor 24, and reset transistor 25 isprovided to one set made up of four photodiodes 21 (21A_1, 21A_2, 21B_1,and 21B_2).

For example, each of the amplification transistor 23, selectingtransistor 24, and reset transistor 25 is provided to the transistorregion TR illustrated in FIG. 16.

(3) Others

While omitted from FIG. 16, a wiring layer (not illustrated) is providedto the surface of the substrate 101. With this wiring layer, wiring (notillustrated) electrically connected to each element is formed within aninsulating layer (not illustrated). Each wiring is layered and formed soas to serve as a wiring such as the transfer line 26, address line 28,vertical signal line 27, reset line 29, or the like, shown in FIG. 17.

In addition, with the substrate 101, optical members such as a colorfilter, micro lenses, and so forth are provided so as to correspond tothe pixels P. Though drawing is omitted, with the color filter, thefilter layer of each color is disposed in the same way as with the firstembodiment, for example, by a Bayer array.

FIGS. 18 and 19 are, with the fourth embodiment of the presentinvention, diagrams illustrating the micro lens 61. Here, FIG. 18illustrates, in the same way as FIG. 16, the upper surface, and FIG. 19illustrates the cross-section of the XIX-XIX portion in FIG. 18. Notethat in FIG. 18, with the lens surface of the micro lens, a portionwhere the curvature is high is indicated by hatching.

As illustrated in FIGS. 18 and 19, the micro lenses 61 are, similar tothe first embodiment, convex lenses with the center being formed thickerthan the edge, and are configured to focus incident light onto thelight-receiving surface of the photodiode.

Here, such as illustrated in FIG. 18, each of the micro lenses 61 is,similar to the first embodiment, formed so that the planar shape is asquare shape. Also, such as illustrated in FIGS. 18 and 19, each of themicro lenses 61 is formed so that the portion of the side correspondingto the transistor region TR is smaller in curvature than other portions.With the portion of the side corresponding to the transistor region TR,each of the micro lenses 61 is formed so that depth Da of a groove to beformed between the micro lenses 61 is shallower than depth Db of thegroove of another portion.

Note that each of the micro lenses 61 can be formed, in the same way aswith the first embodiment, by subjecting the lens material layer to theetchback process after converting the resist pattern into a lens shapesuch as described above.

C. Conclusion

As described above, with the multiple micro lenses 61, the depth Db of agroove between the micro lenses corresponding to a portion where themultiple photodiodes 21 are arrayed on the imaging face (x-y face)without the pixel transistor PTr being introduced therebetween is deeperthan the depth Da of a groove between the micro lenses 61 of anotherportion. Also, the multiple micro lenses 61 are formed so that thecurvature of the lens surface on the side of a portion where themultiple photodiodes 21 are arrayed on the imaging face (x-y face)without the pixel transistor PTr being introduced therebetween is higherthan the curvature of the lens surface of another portion (see FIGS. 18and 19).

Thus, with the present embodiment, the curvature of the lens surface ofthe micro lens 61 is small on the transistor region TR where the pixeltransistor PTr is provided, and accordingly, occurrence of sensitivityunevenness can be prevented, and also influence of reflection from thegate electrode can be suppressed. Also, between the photo diodes 21 ofother than on the transistor region TR, the curvature of the lenssurface of the micro lens 61 is great, and accordingly, occurrence ofcolor mixture can be prevented, and also sensitivity can be improved.

That is to say, regardless of the layout of a wiring layer, between thephotodiodes 21 the accumulation charge of the photodiode 21 is readilyleaked to another pixel at a portion where the pixel transistor PTr isprovided as compared to a portion where no pixel transistor PTr isprovided, but according to the above configuration, occurrence of thisconvenience can be prevented. Accordingly, the present embodiment canreadily improve the image quality of an imaged image.

5. Others

Implementation of the present invention is not restricted to the aboveembodiments, and various modifications may be employed.

FIGS. 20 through 24 are diagrams illustrating the principal portions ofa solid-state imaging device according to an embodiment of the presentinvention. Here, in each drawing, (A) illustrates, in the same way asFIG. 14, the upper surface of the solid-state imaging device excludingthe micro lenses and the like, and (B) illustrates upper surface of thesolid-state imaging device including the micro lenses. Note that (B)illustrates, in the same way as FIG. 16, a portion where the curvatureof the lens surface of the micro lens is high, indicated by hatching.

FIG. 20 illustrates a case where a pixel transistor to be shared isprovided to the transistor region TR as to four pixels P arrayed in thevertical direction y (longitudinal direction).

FIGS. 21 and 22 illustrate a case where a pixel transistor to be sharedis provided to the transistor region TR as to two pixels P arrayed inthe vertical direction y (longitudinal direction). Note that theseconfigurations are described in Japanese Unexamined Patent ApplicationPublication No. 2007-81015. FIG. 23 illustrates a case where a pixeltransistor to be shared is provided to the transistor region TR as totwo pixels P arrayed in the horizontal direction x (lateral direction).FIG. 24 illustrates a case where a pixel transistor is provided to thetransistor region TR as to each pixel P.

With each of the above drawings, in the same way as with the fourthembodiment, the curvature of the lens surface of the micro lens 61 issmall on the transistor region TR, and accordingly, occurrence ofsensitivity unevenness can be prevented, and also influence ofreflection from the gate electrode can be suppressed. Also, thecurvature of the lens surface of the micro lens 61 is great between thephotodiodes 21 other than on the transistor region TR, and accordingly,occurrence of color mixture can be prevented, and also sensitivity canbe improved.

Also, with the above embodiments, description has been made regarding afront illumination type, but the present invention is not restricted tothis. Even in the case of a backside illumination type, the presentinvention may be applied. With a backside illumination type, inparticular, there is inconvenience such as occurrence of color mixturebetween adjacent pixels, or the like, but occurrence of color mixturecan effectively be prevented by applying the present invention thereto.

Note that, with the above embodiments, the solid-state imaging device 1corresponds to the solid-state imaging device described in the Summaryof the Invention. Also, with the above embodiments, the photodiodes 21correspond to the photoelectric conversion units described in theSummary of the Invention. Also, with the above embodiments, the chargetransfer channel region 23T corresponds to the transfer channel regiondescribed in the Summary of the Invention. Also, with the aboveembodiments, the vertical transfer resistor unit VT corresponds to thetransfer unit described in the Summary of the Invention. Also, with theabove embodiments, the micro lens 61 corresponds to the micro lensdescribed in the Summary of the Invention. Also, with the aboveembodiments, the substrate 101 corresponds to the substrate described inthe Summary of the Invention. Also, with the above embodiments, the lensmaterial layer 111 z is the lens material layer described in the Summaryof the Invention. Also, with the above embodiments, the camera 200corresponds to the electronic device described in the Summary of theInvention. Also, with the above embodiments, the light-receiving surfaceJS corresponds to the light-receiving surface described in the Summaryof the Invention. Also, with the above embodiments, the pixels Pcorrespond to the pixels described in the Summary of the Invention.Also, with the above embodiments, the imaging face PS corresponds to theimaging face described in the Summary of the Invention. Also, with theabove embodiments, the pixel transistor PTr corresponds to the pixeltransistor described in the Summary of the Invention. Also, with theabove embodiments, the resist pattern RP corresponds to the resistpattern described in the Summary of the Invention. Also, with the aboveembodiments, the diagonal direction k corresponds to the third directiondescribed in the Summary of the Invention. Also, with the aboveembodiments, the horizontal direction x corresponds to the firstdirection described in the Summary of the Invention. Also, with theabove embodiments, the vertical direction y corresponds to the seconddirection described in the Summary of the Invention.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A solid-state imaging device, comprising: aplurality of photoelectric conversion units in an array along each of afirst direction of an imaging face of a substrate and a second directionorthogonal to said first direction, wherein said plurality ofphotoelectric conversion units is configured to receive incident lightat a light-receiving surface to generate signal charge; a plurality ofmicro lenses in each of said first direction and said second directionabove each light-receiving surface of said plurality of photoelectricconversion units, wherein said plurality of micro lenses is configuredto focus said incident light onto said light-receiving surface; and apixel transistor between said plurality of photoelectric conversionunits of said imaging face, wherein said pixel transistor is configuredto read out and output signal charge generated at said plurality ofphotoelectric conversion units, wherein said plurality of micro lenseshas a planar shape of said imaging face, wherein said planar shapeincludes a portion divided by a first side that extends in said firstdirection and a second side that extends in said second direction,wherein said plurality of micro lenses is arrayed mutually adjacent toeach of said first direction and said second direction, wherein a firstdepth value of a first groove between a first set of micro lenses ofsaid plurality of micro lenses corresponding to a first portion wheresaid plurality of photoelectric conversion units are arrayed withoutsaid pixel transistor between said plurality of photoelectric conversionunits at said imaging face is deeper than a second depth value of asecond groove between a second set of micro lenses corresponding to asecond portion other than said first portion, and wherein a firstcurvature value of a lens surface in said first portion is higher than asecond curvature value of said lens surface in said second portion.
 2. Amethod of manufacturing a solid-state imaging device, said methodcomprising: forming a plurality of photoelectric conversion units whichreceive incident light at a light-receiving surface to generate signalcharge, wherein said plurality of photoelectric conversion units are inan array along each of a first direction of an imaging face of asubstrate and a second direction orthogonal to said first direction;forming a pixel transistor which reads out and outputs signal chargegenerated at said plurality of photoelectric conversion units, whereinsaid pixel transistor is between said plurality of photoelectricconversion units of said imaging face; and forming a plurality of microlenses which focus said incident light onto said light-receivingsurface, wherein said plurality of micro lenses are in each of saidfirst direction and said second direction above each light-receivingsurface of said plurality of photoelectric conversion units, whereinsaid plurality of micro lenses has a planar shape of said imaging face,wherein said planar shape includes a portion divided by a first sidethat extends in said first direction and a second side that extends insaid second direction, wherein said plurality of micro lenses is arrayedmutually adjacent to each of said first direction and said seconddirection, wherein said plurality of micro lenses are formed such that afirst depth value of a first groove between a first set of micro lensesof said plurality of micro lenses corresponding to a first portion wheresaid plurality of photoelectric conversion units are arrayed withoutsaid pixel transistor between said plurality of photoelectric conversionunits at said imaging face is deeper than a second depth value of asecond groove between a second set of micro lenses corresponding to asecond portion other than said first portion, and wherein a firstcurvature value of a lens surface in said first portion is higher than asecond curvature value of said lens surface in said second portion. 3.An electronic device, comprising: a plurality of photoelectricconversion units in an array along each of a first direction of animaging face of a substrate and a second direction orthogonal to saidfirst direction, wherein said plurality of photoelectric conversionunits is configured to receive incident light at a light-receivingsurface to generate signal charge; a plurality of micro lenses in eachof said first direction and said second direction above eachlight-receiving surface of said plurality of photoelectric conversionunits, wherein said plurality of micro lenses is configured to focussaid incident light onto said light-receiving surface; and a pixeltransistor between said plurality of photoelectric conversion units ofsaid imaging face, wherein said pixel transistor is configured to readout and output signal charge generated at said plurality ofphotoelectric conversion units, wherein said plurality of micro lenseshas a planar shape at said imaging face, wherein said planar shapeincludes a portion divided by a first side that extends in said firstdirection and a second side that extends in said second direction,wherein said plurality of micro lenses is arrayed mutually adjacent toeach of said first direction and said second direction, wherein a firstdepth value of a first groove between a first set of micro lenses ofsaid plurality of micro lenses corresponding to a first portion wheresaid plurality of photoelectric conversion units are arrayed withoutsaid pixel transistor between said plurality of photoelectric conversionunits at said imaging face is deeper than a second depth value of asecond groove between a second set of micro lenses corresponding to asecond portion other than said first portion, and wherein a firstcurvature value of a lens surface in said first portion is higher than asecond curvature value of said lens surface in said second portion.